﻿NurbsCurve Constructor (Int32, Boolean, Int32, Int32)

# NurbsCurve Constructor (Int32, Boolean, Int32, Int32)

Constructs a new NURBS curve with knot and CV memory allocated.

Namespace:  Rhino.Geometry
Assembly:  RhinoCommon (in RhinoCommon.dll)
Since: 5.0
Syntax
```public NurbsCurve(
int dimension,
bool rational,
int order,
int pointCount
)```

#### Parameters

dimension
Type: SystemInt32
>=1.
rational
Type: SystemBoolean
true to make a rational NURBS.
order
Type: SystemInt32
(>= 2) The order=degree+1.
pointCount
Type: SystemInt32
(>= order) number of control vertices.
Examples
```using System;

partial class Examples
{
public static Rhino.Commands.Result AddNurbsCircle(Rhino.RhinoDoc doc)
{
// The easy way to get a NURBS curve from a circle is with
// the following two lines of code.
//
// Rhino.Geometry.Circle c = new Rhino.Geometry.Circle(20);
// Rhino.Geometry.NurbsCurve nc = c.ToNurbsCurve();
//
// This sample demonstrates creating a NURBS curve from scratch.
const int dimension = 3;
const bool isRational = true;
const int order = 3;
const int cv_count = 9;
Rhino.Geometry.NurbsCurve nc = new Rhino.Geometry.NurbsCurve(dimension, isRational, order, cv_count);
nc.Points.SetPoint(0, 1.0, 0.0, 0.0, 1.0);
nc.Points.SetPoint(1, 0.707107, 0.707107, 0.0, 0.707107);
nc.Points.SetPoint(2, 0.0, 1.0, 0.0, 1.0);
nc.Points.SetPoint(3, -0.707107, 0.707107, 0.0, 0.707107);
nc.Points.SetPoint(4, -1.0, 0.0, 0.0, 1.0);
nc.Points.SetPoint(5, -0.707107, -0.707107, 0.0, 0.707107);
nc.Points.SetPoint(6, 0.0, -1.0, 0.0, 1.0);
nc.Points.SetPoint(7, 0.707107, -0.707107, 0.0, 0.707107);
nc.Points.SetPoint(8, 1.0, 0.0, 0.0, 1.0);
nc.Knots[0] = 0.0;
nc.Knots[1] = 0.0;
nc.Knots[2] = 0.5 * Math.PI;
nc.Knots[3] = 0.5 * Math.PI;
nc.Knots[4] = Math.PI;
nc.Knots[5] = Math.PI;
nc.Knots[6] = 1.5 * Math.PI;
nc.Knots[7] = 1.5 * Math.PI;
nc.Knots[8] = 2.0 * Math.PI;
nc.Knots[9] = 2.0 * Math.PI;
if (nc.IsValid)
{
doc.Objects.AddCurve(nc);
doc.Views.Redraw();
return Rhino.Commands.Result.Success;
}
return Rhino.Commands.Result.Failure;
}
}```
Python
```using System;

partial class Examples
{
public static Rhino.Commands.Result AddNurbsCircle(Rhino.RhinoDoc doc)
{
// The easy way to get a NURBS curve from a circle is with
// the following two lines of code.
//
// Rhino.Geometry.Circle c = new Rhino.Geometry.Circle(20);
// Rhino.Geometry.NurbsCurve nc = c.ToNurbsCurve();
//
// This sample demonstrates creating a NURBS curve from scratch.
int dimension = 3;
bool isRational = true;
int order = 3;
int cv_count = 9;
Rhino.Geometry.NurbsCurve nc = new Rhino.Geometry.NurbsCurve(dimension, isRational, order, cv_count);
nc.Points.SetPoint(0, 1.0, 0.0, 0.0, 1.0);
nc.Points.SetPoint(1, 0.707107, 0.707107, 0.0, 0.707107);
nc.Points.SetPoint(2, 0.0, 1.0, 0.0, 1.0);
nc.Points.SetPoint(3, -0.707107, 0.707107, 0.0, 0.707107);
nc.Points.SetPoint(4, -1.0, 0.0, 0.0, 1.0);
nc.Points.SetPoint(5, -0.707107, -0.707107, 0.0, 0.707107);
nc.Points.SetPoint(6, 0.0, -1.0, 0.0, 1.0);
nc.Points.SetPoint(7, 0.707107, -0.707107, 0.0, 0.707107);
nc.Points.SetPoint(8, 1.0, 0.0, 0.0, 1.0);
nc.Knots[0] = 0.0;
nc.Knots[1] = 0.0;
nc.Knots[2] = 0.5 * Math.PI;
nc.Knots[3] = 0.5 * Math.PI;
nc.Knots[4] = Math.PI;
nc.Knots[5] = Math.PI;
nc.Knots[6] = 1.5 * Math.PI;
nc.Knots[7] = 1.5 * Math.PI;
nc.Knots[8] = 2.0 * Math.PI;
nc.Knots[9] = 2.0 * Math.PI;
if (nc.IsValid)
{
doc.Objects.AddCurve(nc);
doc.Views.Redraw();
return Rhino.Commands.Result.Success;
}
return Rhino.Commands.Result.Failure;
}
}```
See Also